ANNULAR CATALYTIC CONVERTER

Abstract

The invention relates to an annular catalytic converter, having a first, tubular flow path, having a diverting region (4) and having a second, annular flow path, wherein the tubular flow path is formed by an inner pipe (1), wherein the annular flow path is formed between the inner pipe (1) and an outer pipe (2) surrounding the inner pipe, and the diverting region (4) is of pot-shaped form for the purposes of diverting the exhaust-gas flow from the tubular flow path into the annular flow path, wherein the inner pipe (1) and/or the outer pipe (2) has a conical cross section (D1, D2, D1, D4) that widens or narrows along the flow direction of the exhaust gas.

Claims

1. An annular catalytic converter, having a first, tubular flow path, having a diverting region (4) and having a second, annular flow path, wherein the tubular flow path is formed by an inner pipe (1), wherein the annular flow path is formed between the inner pipe (1) and an outer pipe (2) surrounding the inner pipe, and the diverting region (4) is of pot-shaped form for the purposes of diverting the exhaust-gas flow from the tubular flow path into the annular flow path, characterized in that the inner pipe (1) and/or the outer pipe (2) has a conical cross section (D1, D2, D3, D4) that widens or narrows along the flow direction of the exhaust gas.

2. The annular catalytic converter as claimed in claim 1, characterized in that the inner pipe (1) has a cross section (D1, D3) that widens conically in the flow direction of the exhaust gas and the outer pipe (2) has a cross section (D4, D2) that narrows in the flow direction of the exhaust gas.

3. The annular catalytic converter as claimed in any one of the preceding claims, characterized in that the inner pipe (1) and/or the outer pipe (2) has an oval or an elliptical cross section.

4. The annular catalytic converter as claimed in any one of the preceding claims, characterized in that the inner pipe (1) and the outer pipe (2) have the length (L) and the tubular flow path has a cross-sectional area (D1) at its gas inlet side and the annular flow path has a cross-sectional area (D2) at its gas outlet side, wherein the tubular flow path widens conically from its gas inlet side to its gas outlet side with the angle (al) and the annular flow path narrows conically from its gas inlet side to its gas outlet side with the angle (α2).

5. The annular catalytic converter as claimed in claim 4, characterized in that a particularly preferred size ratio of the annular catalytic converter is defined by the formula $\tan \left(\mathrm{\alpha 2}\right)=\frac{\sqrt{D{2}^2-D{1}^2+(D1+{\left(L*\tan \left(\mathrm{\alpha 1}\right)\right)}^2}-D2}{L}$

6. The annular catalytic converter as claimed in any one of the preceding claims, characterized in that at least one matrix (8) formed by a metallic honeycomb body is arranged in the annular flow path, wherein the matrix (8) has a cross-sectional profile that follows the cross-sectional profile of the annular flow path.

7. The annular catalytic converter as claimed in claim 6, characterized in that the metallic honeycomb body (8) is formed by a multiplicity of metallic foils which are stacked one on top of the other and which are wound up to form the honeycomb body (8), wherein at least some foils are corrugated, wherein the conicity of the metallic honeycomb body (8) and thus of the matrix (8) along its flow direction can be influenced through variation of the corrugation height and of the corrugation density between the gas inlet side and the gas outlet side of the matrix (8).

8. The annular catalytic converter as claimed in any one of the preceding claims, characterized in that the diverting region (4) has a cooling device (5, 6, 7).

9. The annular catalytic converter as claimed in claim 8, characterized in that the cooling device (5, 6, 7) is formed by a double-walled section (5, 6, 7), which can be flowed through by a coolant, of the diverting region (4).

10. The annular catalytic converter as claimed in either one of the preceding claims 8 and 9, characterized in that the cooling device is formed by a cooling coil arranged at or in the diverting region.

11. The annular catalytic converter as claimed in any one of the preceding claims, characterized in that the inner pipe (1) has, at the gas outlet side of the tubular flow path and at the gas inlet side of the annular flow path, a guide element (10) by means of which the exhaust-gas flow flowing through the annular catalytic converter is diverted.

12. The annular catalytic converter as claimed in claim 11, characterized in that the guide element (10) is generated by a bead-like bend of the free end of the inner pipe (1) radially outward and into the annular flow path.

13. The annular catalytic converter as claimed in any one of the preceding claims, characterized in that an optimized incident flow onto a matrix (8) arranged in the annular flow path is achieved by means of the inner wall (5) of the diverting region (4) in conjunction with the guide element (10) on the inner pipe (1).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The invention will be discussed in more detail below on the basis of exemplary embodiments with reference to the drawings. In the drawings:

[0030] FIG. 1 shows a schematic view of the inner pipe and of the outer pipe of an annular catalytic converter for the purposes of illustrating the different cross-sectional areas and angles,

[0031] FIG. 2 shows a schematic sectional view through the annular catalytic converter, wherein the diverting region is of double-walled design and can be flowed through by a coolant, and

[0032] FIG. 3 shows a detail view of the diverting region and of the guide element formed on the inner pipe.

PREFERRED EMBODIMENT OF THE INVENTION

[0033] FIG. 1 shows a schematic view of the inner pipe 2, which is surrounded by the outer pipe 2. The two pipes 1 and 2 are oriented concentrically around the central axis 3. The cross-sectional area D1 is shown at the gas inlet side of the inner pipe 1, whereas the cross-sectional area D3 is illustrated at the gas outlet side of the inner pipe 1. The cross-sectional area D4 or the differential area A2 between the cross-sectional areas D3 and D4 is shown at the gas inlet side of the annular flow path which is formed between the inner pipe 1 and the outer pipe 2. The differential area A1 between the cross-sectional areas D1 and D2 is shown at the gas outlet side of the annular flow path.

[0034] The inner pipe 1 widens from the gas inlet side to the gas outlet side by the angle α1 with respect to the central axis 3. The outer pipe widens from its gas outlet side to its gas inlet side by the angle α2 with respect to the central axis.

[0035] The throughflow sequence is from the gas inlet side of the inner pipe 1 to the gas outlet side of the inner pipe 1, where, in the diverting region not shown in FIG. 1, the exhaust gas is diverted into the gas inlet side of the outer pipe 2 or of the annular flow path. From there, the exhaust gas flows to the gas outlet side of the annular flow path or of the outer pipe 2.

[0036] The pipes 1, 2 have a length L which, in the exemplary embodiment in FIG. 1, is identical for both pipes 1, 2.

[0037] A variation of the angles α1 and α2 leads to different geometries for the tubular flow path and the annular flow path. In particular, the annular flow path may have a cross section that remains constant along the flow direction, or a varying cross section.

[0038] FIG. 2 shows a view of the gas outlet side of the tubular flow path, and the diverting region 4 adjoining said gas outlet side. The diverting region 4 is formed by a pot-shaped wall 5, which serves as a baffle wall for the inflowing exhaust gas and which ultimately serves to divert the exhaust gas outward in a radial direction and ultimately into the annular flow path.

[0039] As can be seen from the arrows in FIG. 2, the main flow direction in the tubular flow path is opposite to the main flow direction in the annular flow path.

[0040] Also shown is a second wall 6, which follows the profile of the inner wall 5 and which thus forms a region 7 through which flow can pass, for example a channel or some other closed volume through which flow can pass. This can be flowed through by a coolant, and thermal energy can thus be dissipated from the exhaust gas via the inner wall 5.

[0041] The free end of the inner pipe 1 furthermore has a bead-like bend radially outward and into the annular flow path. This generates the guide element 10, which is intended to improve the exhaust-gas flow in the volume 9 enclosed by the diverting region 4. The guide element 10 is configured to be of fully encircling form in a radial direction.

[0042] FIG. 3 shows a detail view of the diverting region 4 and in particular of the size ratios of the inner wall 5 and the guide element 10 in relation to the diameter D of the tubular flow path at its gas outlet. A diverting region 4 and a guide element 10 which have dimensions within the magnitudes specified in the table below are particularly advantageous in order to generate the most homogeneous flow possible at the gas inlet of the annular flow path or of the catalytically active matrix 8.

TABLE-US-00001 0.0153 ≤ R1/D ≥ 3.450 0.0153 ≤ R2/D ≥ 3.461 0.0076 ≤ R3/D ≥ 3.461 0.0076 ≤ R4/D ≥ 3.461 0.0153 ≤ R5/D ≥ 3.461 0.0153 ≤ R6/D ≥ 3.461  1.100 ≤ D7/D ≥ 3.461 0.0153 ≤ L1/D ≥ 3.384 0.0076 ≤ L2/D ≥ 3.384 0.0153 ≤ L3/D ≥ 3.384 0.0153 ≤ L4/D ≥ 3.438 0.0153 ≤ L5/D ≥ 3.438 0.0000 ≤ L6/D ≥ 3.469 0.0153 ≤ L7/D ≥ 3.4446 0.0153 ≤ L8/D ≥ 3.450 0.0153 ≤ L9/D ≥ 4.230 0.0460 ≤ L10/D ≥ 3.461 0.0460 ≤ L11/D ≥ 3.461 0.0460 ≤ L12/D ≥ 3.461 0.0153 ≤ L13/D ≥ 3.461 0.0153 ≤ L14/D ≥ 3.461 0.0153 ≤ L15/D ≥ 3.461

[0043] Here, the free end of the inner pipe is bent outward and does not come back into contact with the outer side of the inner pipe. Here, the reference designations L1 to L15 each denote lengths of individual sections. The reference designations R1 to R6 denote different radii of the components. The reference designation D denotes the diameter of the inner pipe at its gas outlet side and the reference designation D7 denotes the diameter of the outer pipe at its gas inlet side.

[0044] The different features of the individual exemplary embodiments can also be combined with one another. The exemplary embodiments in FIGS. 1 to 3 are in particular not of a limiting nature and serve for illustrating the concept of the invention.